The present invention relates primarily to the design and use of cutting and abrading tools and particularly to the shape of the cutting teeth and their edge orientation on the base surface of the tool.
Presently, the base surface of many cutting tools designed and in use for machining, abrading and texturing of elastomers and other non-metallic and composite materials are covered with either various non-oriented hard, abrasive, mono-layered grits, or with solid or structured conical or pyramidal points. For example, U.S. Pat. No. 3,918,217 describes various means to magnetically structure grits of various kinds into conical shaped teeth. U.S. Pat. No. 4,916,869 describes molding of grits into various pyramidal, conical and other shaped armorings made by the use of molds made from models.
Sharp, acute-angled conical or pyramidal tooth points as are known are weak and tend to break off easily or wear away too rapidly. Thus, tool life is relatively short. Further, as the peaks of these teeth become worn, the resultant work piece surface texture changes and eventually becomes unacceptable. Moreover, these pointed tooth designs tend to leave grooved patterns on and into the work pieces; hence the teeth must be truncated by dressing to a common cutting circle, configuration or plane to reduce the inherent grooving. However, truncation increases the truncated width of the tooth which greatly increases friction-caused heat.
Additionally, all such pointed tooth shapes inherently cause a great increase in friction-caused heat because of the rubbing of the rake surfaces against the work piece which is not cut away by the tooth point or truncated edge. This friction-caused heat causes smoke and scorching to the work piece. The adverse affects of the friction-caused heat becomes increasingly severe when mechanically working plastics, all elastomers and other like hydrocarbon materials and composites thereof which are resilient and inherently more sensitive to heat.
Monolayered grits and patterns of such grits usually have inherent truncated, generally obtuse-angled teeth and edges. While stronger and more wear-resistant, these edges cause even greater amounts of friction, and increased energy is used and wasted as frictional heat to the tool and to the work piece. This often tends to scorch or burn the work piece surface and produces objectionable smoke and other undesirable effects to the work pieces such as scorch to elastomers.
Extensive evaluations have been made of the aforementioned limitations of monolayered grits bonded with resin, vitreous, or metal bonds, as well as the limitations inherent to the structured pointed teeth of U.S. Pat. No. 3,918,217 and U.S. Pat. No. 4,916,869, and all other such similar pointed tooth forms such as is disclosed, for example, in U.S. Pat. Nos. 4,460,382, 1,988,065, 3,906,684, 4,539,017, 5,015,266, 5,054,246, 5,064,445, 5,066,312, 5,107,626, 5,152,917, 4,779,386, 4,918,874, 4,776,862, 5,131,924, 5,133,782 and 4,278,448. These studies led to the discovery of the present invention which uses fewer molded, wrought or cast teeth having wider and preferably overlapping edges for the purpose of mechanically working rubbers, elastomers and other non-metallic and hydrocarbon materials and composites thereof, and to cause predetermined surface textures.
The present invention considers the use of any and all hard, natural and man-made grits and particles bonded to each other with resins, vitreous materials or braze metals in the described raised shapes that are not monolayered. The bonding agent usually is used for both bonding of the molded structures as well as bonding the structures to the carriers, resulting in an armed tool. The present invention anticipates that the teeth can also be made of materials used in powder metallurgy and by forming from wrought and cast metals.